1) Field of the Invention
The present invention relates to a cantilever type starter having a pinion at an end portion of a pinion shaft supported by a housing bearing.
2) Description of the Related Art
As one example of conventional technique, there has been known a starter disclosed in Japanese Patent Laid-Open No. 2000-320438. As FIG. 4 shows, this starter is made up of an output shaft 100 to which a motor rotating force is transmitted through a planetary reduction device, a pinion shaft 120 fitted through a pinion bearing 110 over the output shaft 100, a one-way clutch 130 for transmitting the rotation of the output shaft 100 to the pinion shaft 120, and other components, and is equipped with a pinion 150 at a tip portion (end portion on the opposite side to the motor) of the pinion shaft 120 supported by a housing bearing 140.
The one-way clutch 130 is fitted through a helical spline over the output shaft 100 and, when being pushed out in an opposite-of-motor direction by means of attraction of an electromagnetic switch (not shown) at the time of engine starting, it, together with the pinion shaft 120, moves on the output shaft 100 to make the pinion 150 engage with a ring gear 160.
Meanwhile, since the above-mentioned starter has a structure of the pinion shaft 120 and the one-way clutch 130 being moved on the output shaft 100, when the pinion shaft 120 is moved in the opposite-of-motor direction (in the opposite direction with respect to the motor, i.e., in the left-hand direction in the illustration) on the output shaft 100 at the time of engine starting, the axial position of the pinion shaft 110 (which is inserted into the inner circumference of the pinion shaft 120 under pressure) varies with respect to the output shaft 100. Accordingly, the pinion bearing 110 is required to support a rearward portion with respect to the tip portion of the output shaft in the pinion resting condition. That is, if it supports the tip portion of the output shaft 100 in the pinion resting condition, the pinion shaft 120 deviates from the output shaft 100 when moving on the output shaft 100 in the opposite-of-motor direction.
In the case of the above-mentioned construction, the pinion shaft 11 does not move in the motor-of-opposite direction beyond the housing bearing 140, and it is located on the motor side with respect to the housing bearing 140 or located at generally same axial position as the housing bearing 140. Therefore, if a high load is applied onto the pinion 150 when the pinion 15 engages with the ring gear 160 to start the engine, a load works on the one-way clutch 130 with the housing bearing 140 functioning as a supporting point. At this time, there arises a problem in that, since the pinion shaft 120 inclines by an angle corresponding to each of bearing gaps, a roller 130c half-strikes against an outer portion 130a and an inner portion 130b constituting the one-way clutch 130 to cause the clutch 130 to slip.
In addition, when the one-way clutch 130 moves on the output shaft 100 in the opposite-of-motor direction, a portion of a spline 100a provided on the output shaft 100 is exposed and, hence, water, dust or the like entering into the interior of a housing 170 can be attached onto the exposed portion of the spline 100a, thereby inhibiting the one-way clutch 130 from getting back.